Classifications

• • H—ELECTRICITY
  • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
  • H02M—APPARATUS FOR CONVERSION BETWEEN AC AND AC, BETWEEN AC AND DC, OR BETWEEN DC AND DC, AND FOR USE WITH MAINS OR SIMILAR POWER SUPPLY SYSTEMS; CONVERSION OF DC OR AC INPUT POWER INTO SURGE OUTPUT POWER; CONTROL OR REGULATION THEREOF
  • H02M3/00—Conversion of dc power input into dc power output
  • H02M3/02—Conversion of dc power input into dc power output without intermediate conversion into ac
  • H02M3/04—Conversion of dc power input into dc power output without intermediate conversion into ac by static converters
  • H02M3/10—Conversion of dc power input into dc power output without intermediate conversion into ac by static converters using discharge tubes with control electrode or semiconductor devices with control electrode
  • H02M3/145—Conversion of dc power input into dc power output without intermediate conversion into ac by static converters using discharge tubes with control electrode or semiconductor devices with control electrode using devices of a triode or transistor type requiring continuous application of a control signal
  • H02M3/155—Conversion of dc power input into dc power output without intermediate conversion into ac by static converters using discharge tubes with control electrode or semiconductor devices with control electrode using devices of a triode or transistor type requiring continuous application of a control signal using semiconductor devices only
  • H02M3/156—Conversion of dc power input into dc power output without intermediate conversion into ac by static converters using discharge tubes with control electrode or semiconductor devices with control electrode using devices of a triode or transistor type requiring continuous application of a control signal using semiconductor devices only with automatic control of output voltage or current, e.g. switching regulators
  • H02M3/158—Conversion of dc power input into dc power output without intermediate conversion into ac by static converters using discharge tubes with control electrode or semiconductor devices with control electrode using devices of a triode or transistor type requiring continuous application of a control signal using semiconductor devices only with automatic control of output voltage or current, e.g. switching regulators including plural semiconductor devices as final control devices for a single load
  • H02M3/1582—Buck-boost converters
• • H—ELECTRICITY
  • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
  • H02J—CIRCUIT ARRANGEMENTS OR SYSTEMS FOR SUPPLYING OR DISTRIBUTING ELECTRIC POWER; SYSTEMS FOR STORING ELECTRIC ENERGY
  • H02J7/00—Circuit arrangements for charging or depolarising batteries or for supplying loads from batteries
• • H—ELECTRICITY
  • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
  • H02J—CIRCUIT ARRANGEMENTS OR SYSTEMS FOR SUPPLYING OR DISTRIBUTING ELECTRIC POWER; SYSTEMS FOR STORING ELECTRIC ENERGY
  • H02J9/00—Circuit arrangements for emergency or stand-by power supply, e.g. for emergency lighting
  • H02J9/04—Circuit arrangements for emergency or stand-by power supply, e.g. for emergency lighting in which the distribution system is disconnected from the normal source and connected to a standby source
• • H—ELECTRICITY
  • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
  • H02J—CIRCUIT ARRANGEMENTS OR SYSTEMS FOR SUPPLYING OR DISTRIBUTING ELECTRIC POWER; SYSTEMS FOR STORING ELECTRIC ENERGY
  • H02J2207/00—Indexing scheme relating to details of circuit arrangements for charging or depolarising batteries or for supplying loads from batteries
  • H02J2207/20—Charging or discharging characterised by the power electronics converter
• • H—ELECTRICITY
  • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
  • H02J—CIRCUIT ARRANGEMENTS OR SYSTEMS FOR SUPPLYING OR DISTRIBUTING ELECTRIC POWER; SYSTEMS FOR STORING ELECTRIC ENERGY
  • H02J9/00—Circuit arrangements for emergency or stand-by power supply, e.g. for emergency lighting
  • H02J9/04—Circuit arrangements for emergency or stand-by power supply, e.g. for emergency lighting in which the distribution system is disconnected from the normal source and connected to a standby source
  • H02J9/06—Circuit arrangements for emergency or stand-by power supply, e.g. for emergency lighting in which the distribution system is disconnected from the normal source and connected to a standby source with automatic change-over, e.g. UPS systems
  • H02J9/062—Circuit arrangements for emergency or stand-by power supply, e.g. for emergency lighting in which the distribution system is disconnected from the normal source and connected to a standby source with automatic change-over, e.g. UPS systems for AC powered loads
  • H02J9/063—Common neutral, e.g. AC input neutral line connected to AC output neutral line and DC middle point

Definitions

• Embodiments of the present invention relate generally to charging uninterruptable power supply batteries. More specifically, at least one embodiment relates to non-isolated chargers with bi-polar inputs.
• FIG. 1 provides a block diagram of a typical on-line UPS 100 that provides regulated power as well as back-up power to a load 140.
• UPS 's similar to that shown in Figure 1 are available from American Power Conversion (APC) Corporation of West Kingston, RI.
• the UPS 100 includes a rectifier/boost converter 110, an inverter 120, a controller 130, a battery 150, and an isolation transformer charger 160.
• the UPS has inputs 112 and 114 to couple respectively to line and neutral of an input AC power source and has outputs 116 and 118 to provide an output line and neutral to the load 140.
• the rectifier 110 receives the input AC voltage and provides positive and negative output DC voltages at output lines 121 and 122 with respect to a common line 124.
• Isolation transformer charger 160 can be employed to charge battery 150 using an isolation transformer.
• the rectifier 110 upon loss of input AC power, the rectifier 110 generates the DC voltages from the battery 150.
• the common line 124 may be coupled to the input neutral 114 and the output neutral 118 to provide a continuous neutral through the UPS 100.
• the inverter 120 receives the DC voltages from the rectifier 110 and provides an output AC voltage at lines 116 and 118.
• Existing schemes for charging UPS batteries employ an isolated half-bridge topology including a relatively large isolation transformer that is costly, requires a plurality of highly rated associated components, and can saturate due to flux imbalance, causing semiconductor device failure.
• At least one aspect is directed to an uninterruptable power supply having a positive DC bus, a neutral DC bus, and a negative DC bus.
• the uninterruptible power supply includes a battery charger circuit having an inductor, a first charger output, and a second charger output.
• a first switch connected to a first end of the inductor is configured to couple the positive DC bus with the first charger output.
• a second switch connected to a second end of the inductor is configured to couple the negative DC bus with the inductor.
• the neutral DC bus can be coupled to the second charger output.
• the battery charger circuit can be configured to draw power from at least one of the positive DC bus and the negative DC bus to charge a battery coupled to the first charger output and the second charger output.
• At least one other aspect is directed to a method for charging a battery of an uninterruptable power supply having a positive DC bus, a neutral DC bus, and a negative DC bus.
• the method couples at least one of a first charger output of a battery charger circuit with the positive DC bus; and an inductor of the battery charger circuit with the negative DC bus.
• the method couples a second charger output of the battery charger circuit with the neutral DC bus, and applies current from at least one of the positive DC bus and the negative DC bus through the inductor to the battery.
• At least one other aspect is directed to an uninterruptable power supply having a positive DC bus, a neutral DC bus, and a negative DC bus.
• the uninterruptable power supply includes a battery charger circuit having an inductor, a first charger output, and a second charger output.
• the uninterruptable power supply includes means for selectively coupling the first charger output with the positive DC bus; and the inductor with the negative DC bus.
• the second charger output can be coupled to the neutral DC bus.
• the battery charger circuit can be configured to pass current from at least one of the positive DC bus and the neutral DC bus through the inductor to charge a battery.
• Various embodiments of these aspects may include a control module configured to switch the first switch and the second switch in unison.
• a control module can direct the first switch to repeatedly couple and decouple the positive DC bus with the first charger output during a first time period.
• the control module can be configured to direct the second switch to repeatedly couple and decouple the negative DC bus with the inductor during a second time period.
• the first switch can be configured to pass current intermittently from the positive DC bus during a first continuous time period
• the second switch can be configured to pass current intermittently from the neutral DC bus during a second continuous time period.
• the first and second time periods can at least partially overlap.
• the battery charger circuit can be configured to concurrently receive current from the positive DC bus and from the negative DC bus.
• a DC power source can be coupled to at least one of the positive DC bus, the neutral DC bus, and the negative DC bus.
• the uninterruptable power supply can include a control module configured to generate an upper current threshold and a lower current threshold, and to control an inductor current of the inductor to a value between the upper current threshold and the lower current threshold.
• the control module can adjust a first pulse width modulation control signal duty cycle to drive the inductor current below the upper current threshold, and the control module can adjust a second pulse width modulation control signal duty cycle to drive the inductor current above the lower current threshold.
• the battery charger circuit can include a transformer and a resistor, and the control module can be configured to sample at least one of a transformer voltage and a resistor voltage to determine a value of the inductor current.
• Fig. 1 is a functional block diagram illustrating an uninterruptible power supply in a state of operation
• Fig. 2 is a functional block diagram illustrating a battery charger circuit of an uninterruptible power supply in a state of operation
• Fig. 3 is a functional block diagram illustrating a battery charger circuit of an uninterruptible power supply in a state of operation
• Fig. 4 is a functional block diagram illustrating a battery charger circuit of an uninterruptible power supply in a state of operation
• Fig. 5 is a functional block diagram illustrating a battery charger circuit of an uninterruptible power supply in a state of operation
• Fig. 6 is a functional block diagram illustrating a battery charger circuit of an uninterruptible power supply in a state of operation; and Fig. 7 is a flow chart illustrating a method for charging a battery of an uninterruptable power supply in a state of operation.
• At least one embodiment of the present invention provides improved power distribution to a battery, for example, in the uninterruptible power supply of Figure 1.
• embodiments of the present invention are not limited for use in uninterruptible power supplies, and may be used with other power supplies or other systems generally.
• the invention may be embodied in systems and methods for charging a battery of an uninterruptible power supply battery having a positive DC bus, a neutral DC bus, and a negative DC bus.
• These systems and methods can selectively couple at least one of a first charger output of the battery charger circuit with a positive DC bus; and an inductor of the battery charger circuit with the negative DC bus.
• These systems and methods can couple a second charger output of a battery charger circuit with the neutral bus, and can apply power from at least one of the positive and negative buses through the battery charger circuit to the battery.
• Embodiments of the systems and methods disclosed herein can modulate one or more of a plurality of control signal duty cycles to maintain a battery charger circuit inductor current between an upper threshold value and a lower threshold value.
• FIG. 2 is a functional block diagram illustrating a battery charger circuit 200 of an uninterruptible power supply in a state of operation.
• Battery charger circuit 200 generally includes at least positive DC bus 205, neutral DC bus 210, and negative DC bus 215. These bus lines generally transmit or share power between electrical components.
• positive DC bus 205 includes a +400V bus line
• neutral DC bus 210 includes a OV bus line
• negative DC bus 215 includes a - 400V bus line.
• Bus lines 205, 210, and 215 may act as an interface between electrical components.
• each of positive DC bus 205, neutral DC bus 210, and negative DC bus 215 can couple an uninterruptable power supply (not shown in
• battery charger circuit 200 may be included within an uninterruptable power supply.
• bus lines 205, 210, and 215 may include the positive and negative main lines and the neutral line of an uninterruptable power supply rectifier.
• positive DC bus 205, neutral DC bus 210, and negative DC bus 215 can be associated with a power source of an uninterruptable power supply.
• positive DC bus 205 and neutral DC bus 210 connect to opposite sides of at least one first capacitor 220.
• First capacitor 220 in one embodiment can be associated with a voltage source, such as an uninterruptable power supply rectifier.
• First capacitor 220 can be associated, directly or via intervening electrical elements, with an input voltage to an uninterruptable power supply.
• a positive charge side of first capacitor 220 can connect to positive DC bus 205, and a negative charge side of first capacitor 220 can connect to neutral DC bus 210.
• first capacitor 220 can be located between a positive main line and a neutral line of an uninterruptable power supply rectifier.
• Battery charger circuit 200 may also include at least one second capacitor 225, which in one embodiment connects neutral DC bus 210 with negative DC bus 215.
• second capacitor 225 may be associated with a voltage source.
• a positive charge side of second capacitor 225 may connect to neutral bus 210
• a negative charge side of second capacitor 225 may connect to negative bus 215.
• second capacitor 220 can be located between a neutral line and a negative main line of an uninterruptable power supply rectifier.
• either or both of first capacitor 220 and second capacitor 225 can be included within an uninterruptable power supply rectifier.
• Battery charger circuit 200 may also include at least one first switch 230.
• First switch 230 generally includes an electrical or mechanical device that can make or break a connection in a circuit.
• first switch 230 can include at least one transistor.
• first switch 230 includes at least one field effect transistor (FET), although other types of transistors (e.g., bi-polar junction, metal oxide semiconductor field effect transistor, etc. may be used).
• FET field effect transistor
• diode 235 may be a separate element of battery charger circuit 200. Voltage ratings of the components of battery charger circuit 200 may vary. For example, if capacitor 220 and capacitor 225 are each charged to 400V, and capacitor 255 is charged to 200V, each of capacitors 220 and 225 can have a rating of 450V. In this illustrative embodiment, switch 230 and diode 235 can each have a rating of 600V, switch 240 and diode 245 can have a rating of 800V, and capacitor 255 can have a rating of 250V.
• First switch 230 may operate in either of an open state and a closed state, and first switch 230 generally can transition between these two states.
• An open state generally includes no operative circuit connection across first switch 230, (e.g., an open circuit), and a closed state generally does include an operative circuit connection across first switch 230 (e.g., a closed circuit) so that elements on one side of first switch 230 can be electrically coupled to elements on another side of first switch 230.
• first switch 230 when first switch 230 is closed, current can flow from positive DC bus 205 through battery charger circuit 200.
• battery charger circuit 200 can include a closed circuit coupling positive DC bus 205 and neutral DC bus 210 so that current may be provided from positive DC bus 205.
• first switch 230 when first switch 230 is in an open position, battery charger circuit 200 can include an open circuit so that positive DC bus 205 and neutral DC bus 210 are not coupled. In this embodiment where first switch 230 is open, current is not drawn from positive DC bus 205.
• Battery charger circuit 200 may also include at least one second switch 240.
• Second switch 240 may include at least one transistor. Second switch 240 may operate in either of an open state and a closed state, and can generally transition between these two states.
• An open state generally includes no operative circuit connection across second switch 240
• a closed state generally does include an operative circuit connection across second switch 240 so that elements on one side of second switch 240 can be electrically coupled to elements on another side of second switch 240.
• battery charger circuit 200 when second switch 240 is closed, current can flow from neutral DC bus 210 through battery charger circuit 200.
• battery charger circuit 200 can include a closed circuit coupling neutral DC bus 210 and negative DC bus 215 so that current may be provided from neutral DC bus 210.
• battery charger circuit 200 when second switch 240 is in an open position, battery charger circuit 200 can include an open circuit so that neutral DC bus 210 and negative DC bus 215 are not coupled. In this embodiment where second switch 240 is open, current is not drawn from negative DC bus 215.
• Battery charger circuit 200 may include at least one battery 250 and at least one capacitor 255.
• battery 250 can include at least one battery string.
• battery 250 when an uninterruptable power supply including battery charger circuit 200 is in a battery mode of operation, battery 250 can provide power to the uninterruptable power supply.
• the power output by battery 250 may be applied to, for example, uninterruptable power supply components such as an inverter, or directly to a load associated with the uninterruptable power supply.
• battery 250 can include at least one positive terminal V BATT + and at least one negative terminal V BATT • As illustrated in Figure 2, positive terminal V BATT + may connect to first charger output 260 and negative terminal V BATT " may connect to second charger output 265. It should be appreciated that in various embodiments these connections may be reversed so that first charger output 260 can connect to negative terminal V BATT " and second charger output 265 can connect to positive terminal V BATT + - In one embodiment, first charger output 260 can couple a terminal, such as positive terminal V BATT + of battery 250 with positive DC bus 205.
• coupling between positive DC bus 205 and battery 250 via first charger output 260 can include various components of battery charger circuit 200, such as first switch 230, diode 245, and other components described herein as illustrated, for example, in Figure 2.
• second charger output 265 can couple a terminal, such as negative terminal V BATT " of battery 250 with neutral bus line 210. It should be appreciated that the embodiment illustrated in Figure 2 may be reversed so that second charger output 265 couples with positive terminal V BATT + of battery 250, and negative terminal V BATT " of battery 250 couples with first charger output 260.
• battery charger circuit 200 can include at least one control module 270.
• Control module 270 generally controls the switching of, for example, any of first switch 230 and second switch 240.
• Control module 270 can sense current in battery charger circuit 200 such as current through inductor 275.
• Control module 270 may include at least one processor or circuit configured to perform logic operations that, for example, control the switching of first switch 230 or second switch 240 between open and closed states.
• control module 270 is the main controller of an uninterruptable power supply containing the charging circuit.
• control module 270 may include at least one control signal generator to generate, for example, a pulse with modulation control signal having a duty cycle that can be applied to first switch 230 or second switch 240 to control switching operations.
• a pulse width modulation control signal having a first duty cycle can be applied to first switch 230 and a pulse with modulation control signal having a second duty cycle can be applied to second switch 240.
• the first duty cycle (applied to first switch 230) and the second duty cycle (applied to second switch 240) can be different duty cycles.
• Battery charger circuit 200 may include at least one inductor 275, which may have, for example, an inductance tolerance of less than 15%, although other tolerances are possible.
• a first end of inductor 275 can be connected to first switch 230, and a second end of inductor 275 can be connected to second switch 240.
• current through inductor 275 may be provided from positive DC bus 205 and neutral DC bus 210, depending on the state of first switch 230 and second switch 240. For example, when first switch 230 is closed, (i.e., forming a connection) current through inductor 275 can be provided in a path from positive DC bus 205 to neutral DC bus 210. Continuing with this illustrative embodiment, when second switch 240 is closed, current through inductor 275 can be provided in a path from neutral DC bus 210 to negative DC bus 215. In one embodiment, first switch 230 and second switch 240 can be closed simultaneously. In this embodiment, current through inductor 275 can concurrently be provided from both positive DC bus 205 and neutral DC bus 210.
• current from at least one of positive DC bus 205 and negative DC bus 215 may pass through inductor 275 and along first charger output 260 to charge battery 250.
• second charger output 265 may be coupled with neutral DC bus 210.
• first switch 230 and second switch 240 may switch alternately, so that when one switch is open, the other is generally closed.
• first switch 230 and second switch 240 may switch at 50 kHz.
• dissipation in first switch 230 and second switch 240 can occur at half of the inductor frequency of inductor 275.
• first switch 230 and second switch 240 may switch in unison, so that both switches are in a same state at a same time.
• first switch 230 and second switch 240 may both be open for all or part of a same time period.
• first switch 230 and second switch 240 may both be closed for all or part of a same time period.
• each of first switch 230, second switch 240, and inductor 275 can operate at a same frequency, such as 100 kHz, for example.
• these components may operate at frequencies that vary, for example, from 20 kHz to 150 kHz.
• first switch 230 can repeatedly switch states (e.g., from open to closed) while second switch 240 remains in a same state, (e.g., open).
• first switch 230 repeatedly switches from an open position to a closed position over a period of time while second switch 240 remains open
• current can be provided to inductor 275 from positive DC bus 205.
• This time period may be, for example 10ms, although other time periods are possible.
• first switch 230 cycles between states while second switch 240 remains open, current can be provided to inductor 275 from only positive DC bus 205. It should be appreciated that in other embodiments a current path can be provided to inductor 275 from either or both of positive DC bus 205 and neutral DC bus 210 at either the same or different times.
• first switch 230 switches between states while second switch 240 remains open
• the operations of first switch 230 and second switch 240 can reverse, i.e., first switch 230 remains in one state (e.g., open) while second switch 240 repeatedly switches states over a time period, (i.e., repeatedly opens and closes).
• current may be provided to inductor 275 from neutral DC bus 210 while second switch 240 is cycling and first switch 230 remains open.
• these cycling operations may continue, where one switch repeatedly switches states between open and closed while another switch remains in a single state, which in various embodiments can be either an open state or a closed state.
• second switch 240 may oscillate between open and closed states with first switch 230 in an open state for a first time period of 10ms. After the first time period, second switch 240 may remain in a single state (e.g., open) while first switch 230 oscillates between open and closed states for a second time period, which may but need not also be 10ms.
• elements of battery charger circuit 200 such as inductor 275 can be provided current from at least one of positive DC bus 205 and neutral DC bus 210. This may occur alternately or concurrently, or during consecutive, overlapping, or partially overlapping time periods, for example.
• control module 270 can sense a current of inductor 275.
• control module 270 may sample, sense, or otherwise receive or obtain an indication of a voltage of at least one of resistor 280 or transformer 285.
• control module 270 can obtain a secondary voltage of current transformer 285, which may include, for example, a transformer having a 1:100 turn ratio with a tolerance of less than 5%.
• voltages of resistor 280 and transformer 285 can be summed to provide inductor current feedback to controller 270. Controller 270 may then use inductor current feedback based on voltage measurements of at least one of resistor 280 and transformer 285 to control the current of inductor 275 to regulate battery 250 voltage or current.
• control module 270 employs hysteretic control that generally controls the current of inductor 275 so that, for example, inductor current may remain within a range, which can be defined by an upper threshold and a lower threshold.
• battery charger circuit 200 may include current sense transformer 285 and current sense resistor 280 that can sense the inductor current. This sensed inductor current may be evaluated against the upper and lower threshold to determine if the inductor current is within the range.
• control module 270 when information from transformer 285 or resistor 280 indicates that inductor current is approaching or below a minimum threshold, control module 270 can close at least one of first switch 230 and second switch 240, creating a path for current to flow to inductor 275 from at least one of positive bus 205 and neutral bus 210. In one embodiment, when information from one or more of resistor 280 and transformer 285 indicates that inductor current is too high, (e.g., approaching or exceeding a maximum threshold) control module 270 may open, for example, first switch 230, which interrupts current flow from positive bus 205 to inductor 275, lowering inductor current.
• control module 270 may control inductor current based on information related to a voltage of battery 250. For example, in various embodiments if battery 250 voltage is either above or below a threshold, control module 270 may either open or close one of first switch 230 and second switch 240 to either provide or remove a path for current to flow through inductor 275. In one embodiment, the upper and lower thresholds can vary based on the voltage of battery 250.
• Control module 270 may employ pulse width modulation (PWM) techniques that do not include fixed frequency control. However, in one embodiment, fixed frequency control can be used where, for example, switches 230 and 240 do not alternate every switch cycle.
• control module 270 may include at least one control signal generator to produce one PWM control signal for each of first switch 230 and second switch 240. A different duty cycles may be associated with each PWM control signal controlled by control module 270.
• Control module 270 may adjust a duty cycle of a PWM control signal to, for example, switch a state of at least one of first switch 230 and second switch 240 to increase or decrease current flow through inductor 275.
• control module 270 may apply a duty cycle to first switch 230 and apply a different duty cycle to second switch 240.
• the collective application of various duty cycles from control module 270 to at least one of first switch 230 and second switch 240 maintains inductor current at a level between an upper current threshold and a lower current threshold.
• upper and lower thresholds used to control a duty cycle associated with first switch 230 can be different from upper and lower thresholds used to control a duty cycle associated with second switch 240.
• control module 270 can adjust a PWM control signal duty cycle to control the inductor current between upper and lower thresholds.
• first switch 230 may switch from a closed position to an open position to cut off the flow of current from positive DC bus 205 through inductor 275, which can decrease the inductor current.
• second switch 240 can switch from an open position to a closed position to enable the flow of current from negative DC bus 215 through inductor 275 to increase.
• control module 270 can control the state of switches such as either or both of first switch 230 and second switch 240 using hysteretic control. This can regulate the current flow from any of positive DC bus 205, neutral DC bus 210, and negative DC bus 215. This current may flow through inductor 275 and may be applied to battery 250 via at least one of first charger output 260 and second charger output 265. Applying current to battery 250 generally charges battery 250.
• first switch 230 and second switch 240 may be opened or closed to regulate, for example the current flow from any of positive DC bus 205, neutral DC bus 210, and negative DC bus 215, the current or voltage of inductor 275, and the current or voltage applied to battery 250.
• the nomenclature of identifying first and second elements of battery charger circuit 200 is not intended to be limiting.
• first and second elements such as first switch 230 and second switch 240, or first charger output 260 and second charger output 265 can be equivalent or interchangeable elements.
• Figure 3 is a functional block diagram illustrating battery charger circuit 200 of an uninterruptible power supply in a state of operation.
• first switch 230 is in a closed position and second switch 240 is in an open position.
• closed first switch 230 completes a circuit between positive DC bus 205 and battery 250.
• inductor 275 can be provided current from positive DC bus 205 that can be applied to battery 250 via first charger output 260. It should be appreciated that providing current from any of positive DC bus 205, neutral DC bus 210, or negative DC bus 215 can include providing current from a power source coupled to any of these bus lines.
• switch 240 is open and inductor 275 in this example is not drawing current from negative DC bus 215.
• first switch 230 is connected to a first end of inductor 275.
• Current can pass through closed first switch 230, through inductor 275 and to battery 250 via first charger output 260.
• inductor 275 can be charged when current flows through it from, for example, one of the DC bus lines. In this embodiment inductor current may increase with time. In another embodiment, inductor 275 can discharge when current drains from inductor 275 to battery 250, and in this embodiment inductor current may decrease with time.
• Figure 3 illustrates current loop 305, which generally depicts current travelling through battery charger circuit 200 in the embodiment of Figure 3, where first switch 230 is closed and second switch 240 is open.
• battery charger circuit 200 may draw current from a voltage source connected to positive DC bus 205 and neutral DC bus 210 through first switch 230 and inductor 275, and apply the current to battery 250.
• control module 270 can close first switch 230 to draw current from positive DC bus 205, increasing current through inductor 275 to charge battery 250.
• first switch 230 is closed while second switch 240 is open, it should be appreciated that about half of the voltage of battery charger circuit 200, (200V in one example) may be applied to inductor 275 with, for example, another 200V applied across battery 250 or capacitor 255.
• FIG. 4 is a functional block diagram illustrating battery charger circuit 200 of an uninterruptible power supply in a state of operation.
• both first switch 230 and second switch 240 are open.
• both positive DC bus 205 and negative DC bus 215 are electrically cut off from inductor 275.
• current from at least one of positive DC bus 205 and neutral DC bus 210 may circulate through current loop 405 through inductor 275 and across capacitor 255.
• the state of operation of battery charger circuit 200 may change with time. If a state of operation prior to the state of operation depicted in Figure 4 included an embodiment where first switch 230 was closed, current may have been provided from positive DC bus 205; if second switch 240 was closed, current may have been provided from neutral DC bus 210; and if both first switch 230 and second switch 240 were closed, current may have been provided from both positive DC bus 205 and neutral DC bus 210.
• current present in current loop 405 may pass through inductor 275 and first charger output 260 to charge battery 250.
• control module 270 may open both first switch 230 and second switch 240 because, for example, inductor current is approaching or exceeding an upper threshold value.
• first switch 230 and second switch 240 may be open at the same time to avoid overloading, for example, battery 250, resistor 280, transformer 285, other elements of battery charger circuit 200, an uninterruptable power supply, or its load.
• Figure 5 is a functional block diagram illustrating battery charger 200 circuit of an uninterruptible power supply in a state of operation. In the embodiment of Figure 5, first switch 230 is open and second switch 240 is closed. In embodiments where second switch 240 is in a closed position, such as the embodiment illustrated in Figure 5, inductor 275 can receive current from neutral DC bus 210 through inductor 275.
• control module 270 may close second switch 240 to increase inductor current flowing through inductor 275 in the path generally indicated by current loop 505.
• inductor current may then be applied to battery 250 via current loop 405, as depicted in Figure 4.
• second switch 240 is closed while first switch 230 is open, it should be appreciated that all or substantially all of the voltage of battery charger circuit 200, (400V in one example) may be applied to inductor 275.
• the inductor current is alternately increasing (as current is provided from neutral DC bus 210) and decreasing (as current is drained to battery 250).
• battery charger circuit 200 operates to charge battery 250 by repeatedly changing states of operation between those of Figures 4 and 5. It should also be appreciated that repeatedly changing states of operation between those of Figures 3 and 4 results in an increase in inductor current (as current is provided from positive DC bus 205) and a decrease in inductor current (as current is drained to battery 250).
• FIG. 6 is a functional block diagram illustrating battery charger circuit 200 of an uninterruptible power supply in a state of operation.
• both first switch 230 and second switch 240 are closed.
• closed switches 230 and 240 enable inductor 275 to charge from both positive DC bus 205 (due to closed first switch 230) and from neutral DC bus 210 (due to closed second switch 240).
• current loop 305 can charge inductor 275 from positive DC bus 205 and apply at least some of this power to battery 250 via first input line 260.
• current loop 505 can charge inductor 275, and this charge may then drain into battery 250 via current loop 305, for example.
• At least one of first switch 230 and second switch 240 being in a closed condition can cause an increase in inductor current.
• control module 270 may close one or both of first and second switches 230 and 240 to drive inductor current above a threshold.
• control module 270 may open one or both of first switch 230 and second switch 240, (as illustrated in Figures 3 - 5).
• first switch 230 and second switch 240 may be switching between open and closed states with time and in a variety of patterns, which may overlap.
• first switch 230 and second switch 240 may be open, closed, transitioning from opened to closed, or transitioning from closed to open, for example. It should be appreciated that in various embodiments modified configurations of battery charger circuit 200 are possible.
• any of positive DC bus 205, neutral DC bus 210, and negative DC bus 215 can couple with any terminal of battery 250 via any of first charger output 260, second charger output 265, and intervening circuit components, such as those illustrated in the Figures, or other components or topologies.
• Battery charger circuit 200 can be compatible with any topology where, for example, positive and negative DC buses used as inputs to charge a battery where one terminal of the battery is connected to a midpoint or neutral line of the positive and negative DC buses. This may include, for example, a double conversion uninterruptable power supply.
• Fig. 7 is a flow chart illustrating a method 700 for charging a battery of an uninterruptable power supply in a state of operation.
• the uninterruptable power supply includes a positive DC bus, a neutral DC bus, and a negative DC bus.
• Method 700 may include the act of coupling a first charger output of a battery charger circuit with the positive DC bus (ACT 705). Coupling the first charger output with the positive DC bus (ACT 705) may include connecting positive DC bus associated with a source voltage to a battery via a charger output connected to a battery terminal.
• positive DC bus coupling act (ACT 705) can include connecting the first charger output with the positive DC bus via one or more intervening elements of a battery charger circuit, such as one or more transformers, diodes, inductors, or switches, for example.
• coupling the first charger output with the positive DC bus can include performing a first switching operation at a first end of an inductor of a battery charger circuit. For example a switching operation may close a switch to complete an electrical connection that couples, for example, a DC bus with a battery input line (ACT 705). In one embodiment, this first switching operation may be performed more than once during a time period to repeatedly couple and decouple a DC bus with a battery input line. In various embodiments, coupling the positive DC bus with a first charger output (ACT 705) allows an inductor of a battery charger circuit to be charged from the positive DC bus, and to supply power to a battery associated with the battery charger circuit.
• Method 700 may also include the act of coupling at least one inductor of a battery charger circuit with a negative DC bus (ACT 710).
• inductor coupling act (ACT 710) can include connecting an inductor of the battery charger circuit with a negative DC bus either directly or via intervening elements of a battery charger circuit, such as a switch for example.
• Method 700 in various embodiments may perform any of positive DC bus coupling (ACT 705), negative DC bus coupling (ACT 710), or both positive DC bus coupling (ACT 705) and negative DC bus coupling (ACT 710).
• coupling a DC bus with an inductor can include performing a second switching operation at a second end of the inductor.
• a switching operation may close a switch to complete an electrical connection that couples, for example, a DC bus with the inductor (ACT 710).
• this second switching operation may be performed more than once during a time period to repeatedly couple and decouple a negative DC bus with the inductor.
• coupling the negative DC bus with the inductor (ACT 710) allows the inductor to be charged from the neutral DC bus, and this charge may then be supplied to charge a battery associated with the battery charger circuit.
• method 700 can perform the act of coupling a second charger output of a battery charger circuit with a neutral DC bus (ACT 715).
• a battery terminal may connect to or otherwise interface with a charger output of a battery charger circuit, and the charger output may connect to a neutral DC bus associated with a power source.
• neutral DC bus may form a closed circuit with the inductor and at least one of positive DC bus and negative DC bus.
• any coupling act described herein such as positive DC bus coupling act (ACT 705), negative DC bus coupling act (ACT 710), or neutral DC bus coupling act (ACT 715) may include electrically connecting at least two elements directly or via one or more intervening elements, such as various circuit components.
• Method 700 in one embodiment can include the three coupling acts described above, (ACT 705, ACT 710, and ACT 715) which couple, respectively, a positive DC bus, a negative DC bus, and a neutral DC bus with a battery charger circuit that can include two charger outputs to a battery, for example a first charger output that connects to a first battery terminal, and a second charger output that connects to a second battery terminal.
• method 700 can include an embodiment where a voltage source having three outputs, (e.g., positive, negative, and neutral) charges a battery having two terminals, (e.g., positive and negative).
• a voltage source having three outputs e.g., positive, negative, and neutral
• at least one battery terminal can couple with or otherwise connect to the neutral output of the voltage source (i.e., a neutral DC bus) and the other battery terminal can couple with either the positive output of the voltage source or the negative output of the voltage source (i.e., positive DC bus or negative DC bus).
• method 700 can perform the act of applying current through an inductor of a battery charger circuit to a battery (ACT 720).
• applying current can include applying current from at least one of a positive DC bus and a neutral DC bus through the inductor to the battery.
• at least one of first and second switching operations can control inductor current in a path from at least one of positive DC bus and neutral DC bus through the inductor to charge a battery (ACT 720).
• Method 700 generally includes control of first and second switching operations to regulate current drawn from, for example, the positive DC bus or the negative DC bus as a result of at least one of positive DC bus coupling act (ACT 705), negative DC bus coupling act (710), and neutral DC bus coupling act (ACT 715).
• controlling first and second switching operations controls inductor current by regulating the amount of current drawn to or drained from the inductor.
• the elements or acts of Figures 1 - 7 include the elements of uninterruptable power supply 100.
• control module 270 includes controller 130
• battery 250 includes battery 150, for example.
• battery charger circuit 200 can include elements not shown that correspond to elements of Figure 1, such as multiple input, output, or neutral lines, for example.
• the enumerated items are shown as individual elements. In actual implementations of the systems and methods described herein, however, they may be inseparable components of other electronic devices such as a digital computer.
• at least some of the elements and acts described above may be implemented at least in part in software that may be embodied at least in part in an article of manufacture that includes a program storage medium.
• the program storage medium can include one or more of a carrier wave, a computer disk (magnetic, or optical (e.g., CD or DVD, or both), non-volatile memory, tape, a system memory, and a computer hard drive.
• the systems and methods described herein afford a simple and effective way to charge a battery of an uninterruptable power supply.
• the systems and methods according to various embodiments are able to charge a battery by connecting one terminal of the battery to a neutral bus line of a voltage source and to connect the positive and negative bus lines of the DC source to circuit elements to charge the battery. This eliminates the need for isolated half bridge topologies including isolation transformers and associated components, which increases efficiency and reliability while reducing size and lowering cost.
• references to embodiments or elements or acts of the systems and methods herein referred to in the singular may also embrace embodiments including a plurality of these elements, and any references in plural to any embodiment or element or act herein may also embrace embodiments including only a single element. References in the singular or plural form are not intended to limit the presently disclosed systems or methods, their components, acts, or elements. Any embodiment disclosed herein may be combined with any other embodiment, and references to "an embodiment”, “some embodiments”, “an alternate embodiment”, “various embodiments", “one embodiment”, or the like are not necessarily mutually exclusive. Any embodiment may be combined with any other embodiment in any manner consistent with the objects, aims, and needs disclosed herein.

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• Engineering & Computer Science (AREA)
• Power Engineering (AREA)
• Business, Economics & Management (AREA)
• Emergency Management (AREA)
• Charge And Discharge Circuits For Batteries Or The Like (AREA)
• Secondary Cells (AREA)
• Stand-By Power Supply Arrangements (AREA)

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